SCN5A and breast carcinoma: We therefore evaluated the effect of both compounds on Nav1.5 current properties using whole-cell patch clamp recording, employing a two-pronged approach: (1) recording Nav1.5 currents endogenously expressed in the MDA-MB-231 breast cancer cell line (Roger et al., 2003; Fraser et al., 2005; Brackenbury et al., 2007), and (2) recording from Nav1.5 stably over-expressed in HEK-293 cells (HEK-Nav1.5) (Patino et al., 2011).